This section provides background information to facilitate a better understanding of the various aspects of the present invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
After a well has been drilled and casing has been cemented in the well, one or more sections of the casing, which are adjacent to the surrounding geological formation (e.g., zones), may be perforated to provide fluid from between the formation and the well (e.g., for production and/or injection). A perforating gun string may be lowered into the well to a desired depth and the gun(s) fired to create openings in the casing and to extend perforations (e.g., tunnels) into the surrounding formation.
Typically, perforating guns (which include gun carriers and shaped charges mounted on or in the gun carriers) are lowered through tubing or other pipes to the desired well interval. Shaped charges carried in a perforating gun are often phased to fire in multiple directions around the circumference of the wellbore. When fired, shaped charges create perforating jets that form holes in surrounding casing as well as extend perforations into the surrounding formation.
Various types of perforating guns exist. One type of perforating gun includes capsule shaped charges that are mounted on a strip in various patterns. The capsule shaped charges are protected from the harsh wellbore environment by individual containers or capsules. Another type of perforating gun includes non-capsule shaped charges, which are loaded into a sealed carrier for protection. Such perforating guns are sometimes also referred to as hollow carrier guns. The non-capsule shaped charges of such hollow carrier guns may be mounted in a loading tube that is contained inside the carrier, with each shaped charge connected to a detonating cord. When activated, a detonation wave is initiated in the detonating cord to fire the shaped charges. Upon firing, the shaped charge emits sufficient energy to collapse the liner and to form a high-velocity high-density jet which perforates the hollow carrier (or cap, in the case of a capsule charge) and subsequently the casing and surrounding formation.
Traditionally shaped charge liners for oilfield perforating activities have been fabricated by pressing solid metal sheets and/or by pressing powdered metal compositions into the final shape. Pressing solid sheets of metal alloys is limited by the ability to plastically deform the sheets to the desired shape without shrinking, tearing, and work hardening for example. Utilizing solid sheets may create large particle debris when the shaped charged is detonated resulting in an increased tendency to plug the perforation tunnel (e.g., hole) created by the detonated shaped charge.
Pressed metal powders have provided smaller particle sizes upon detonation relative to solid metal sheets resulting in less of a barrier to fluid flow through the perforation tunnel. However, pressing metal powders into generally conical shaped liners has tended to result in liners that have a non-uniform distribution of material. If the metal powder distribution is not uniform the liner will have density variations along the vertical and radial axis and the geometrical symmetry will suffer. Further, pressing can typically only be accomplished in the axial direction and not in the radial direction.